Lufthansa, Germany’s biggest airline, has canceled around 350 flights in Frankfurt, Berlin and Munich, leaving 26,000 passengers stranded. Crew will strike for a further 24 hours on Friday in a row that is causing millions of euros in losses.

­Cabin crew members in Frankfurt and Berlin and Munich are protesting over their pay and conditions.

Germany's Independent Flight Attendants Organization (UFO in German), the labor union that represents the majority of Lufthansa's 18,000 cabin crew members, is demanding a 5 per cent increase in salaries from the company, along with guarantees against outsourcing and the use of temporary employees.

In return, the air carrier has offered a 3.5 per cent salary increase – in return for longer working hours – a deal the employees have refused.

Frankfurt, the third-busiest airport in Europe, remained closed for several hours because of the strike. Berlin’s Tegel airport has also been affected.

UFO members are also calling for the country’s second-largest airport, Munich, to join the strike at 11:00 GMT.

Lufthansa has not yet given any estimates of the damage triggered by the congestion in Berlin and Munich.

The air carrier has announced that only a handful of long-distance flights will be affected by the move. Around half of short- and medium-distance flights have been canceled, though.

The carrier is currently cutting its budget by 1.5 billion euro, a measure designed to fight rising fuel costs and competition from low-cost and Gulf airlines.

This strike comes days after another massive walk-out was organized at Frankfurt airport, bringing the facility to a standstill and also leaving thousands of passengers stranded.

Lufthansa employees strike on September 4, 2012 at the airport in Frankfurt/M.(AFP Photo / Frank Rumpenhorst)

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A Lufthansa employee holds up a poster as he strikes on early September 4, 2012 at the airport in Frankfurt/M.(AFP Photo / Frank Rumpenhorst)

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Passengers wait for their transfer at the Fraport airport in Frankfurt, September 4, 2012.(REUTERS / Kai Pfaffenbach)

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Passengers rest, wrapped in the blankets of German air carrier Lufthansa as they wait for their transfer at the Fraport airport in Frankfurt, September 4, 2012.(REUTERS / Kai Pfaffenbach)

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Nicoley Baublies (R), head of German air carrier Lufthansa cabin crew union "UFO," poses for a picture during a strike at the Fraport airport in Frankfurt, September 4, 2012.(REUTERS / Kai Pfaffenbach)

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Flight passengers wait on September 4, 2012 at the airport in Frankfurt/M.(AFP Photo / Frank Rumpenhorst)

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Flight passengers wait on September 4, 2012 at the airport in Frankfurt/M.(AFP Photo / Frank Rumpenhorst)